title: Carbon nanotube-based symbiotic coaxial nanocables with nanosilica and nanogold particles as labels for electrochemical immunoassay of carcinoembryonic antigen in biological fluids.
abstract: A feasible and practicable amperometric immunoassay strategy for sensitive screening of carcinoembryonic antigen (CEA) in human serum was developed using carbon nanotube (CNT)-based symbiotic coaxial nanocables as labels. To construct such a nanocable, a thin layer of silica nanoparticles was coated on the CNT surface by sonication and sol-gel methods, and then colloidal gold nanoparticles were assembled on the amino-functionalized SiO(2)/CNTs, which were used for the label of horseradish peroxidase-anti-CEA conjugates (HRP-anti-CEA-Au/SiO(2)/CNT). In the presence of analyte CEA, the sandwich-type immunocomplex was formed on an anti-CEA/Au/thionine/Nafion-modified glassy carbon electrode by using HRP-anti-CEA-Au/SiO(2)/CNTs as detection antibodies. To embody the advantages of the protocol, the analytical properties of variously modified electrodes were compared in detail on the basis of different nanolabels. Under optimal conditions, the cathodic peak currents of the electrochemical immunosensor were proportional to the logarithm of CEA concentration over the range from 0.01 to 12 ng mL(-1) in pH 5.5 HAc-NaAc containing 5mM H(2)O(2). At a signal-to-noise ratio of 3, the detection limit (LOD) is 5 pg mL(-1) CEA. Intra- and inter-assay coefficients of variation were below 9.5%. Meanwhile, the selectivity and stability of the immunosensor were acceptable. In addition, the technique was evaluated by spiking CEA standards in pH 7.4 PBS and with 35 clinical serum specimens, receiving excellent accordance with results from commercially available electrochemiluminescent enzyme-linked immunoassay.
authors.affiliation: Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Qunfang
authors.initials: Q
authors.lastname: Li
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.forename: Biling
authors.initials: B
authors.lastname: Su
authors.forename: Jianxin
authors.initials: J
authors.lastname: Huang
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D002272:Carcinoembryonic Antigen / Q000097:blood*; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay; D057230:Limit of Detection; D053768:Metal Nanoparticles; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D002272:Carcinoembryonic Antigen; D037742:Nanotubes, Carbon; D006046:Gold; D012822:Silicon Dioxide